DESCRIPTION Hypertension is considered one of the major causes of end stage renal disease (ESRD) in the general population, and the number one cause in African Americans. Despite the availability of potent antihypertensive drugs, the number of hypertensive African Americans progressing to ESRD continues to rise. This disproportionately high prevalence of ESRD in African Americans cannot be explained by the higher prevalence of hypertension. Whether this is due to more susceptibility of the kidney of African Americans to hypertensive injury or due to concurrent existence of unidentified renal factors is not known. There is preliminary evidence suggesting that antihypertensive drugs may retard the progression of hypertensive renal disease, but no clinical trial has been conducted to test this hypothesis in African Americans. This proposed multi-center project is designed to study the following: if the pathological lesion in "hypertensive renal disease" is purely a result of persistent hypertension; if one anti-hypertensive drug is better than another in terms of preservation of renal function; and the level of blood pressure suitable for the survival of the kidney. Hypertensive African Americans, 18-70 years of age with no other known disease that can affect the kidney, will be screened for blood pressure qualification, and will undergo glomerular filtration rate (GFR) tests. Those who qualify, based on blood pressure levels and the GFR results will then be randomized in a double-masked fashion to one of the three major antihypertensive classes (converting enzyme inhibitor, calcium channel blocker, or beta blocker) and to one of two pressure levels: mean blood pressure greater than 92 millimeter of mercury (mmHg), or 102 to 107 mmHg. Other antihypertensive drugs will be added to keep the blood pressure at the desired level. The blood pressure of the randomized subjects will then be monitored on a monthly basis and compliance to medication(s) will be checked at the same time. Their renal function will also be tracked with periodic GFR tests throughout the study period, which will last approximately four years. All data will be collected and sent to the Data Coordinating Center (DCC) for analyses and interpretation. The goal of the African American Study of Kidney Disease and Hypertension (AASK) full- scale trial is to better understand the physiopathology of hypertensive renal disease in an effort to develop guidelines to prevent the increasing prevalence of ESRD in African Americans.